In the production of earth bore holes that extend from one side of an obstruction to the other a slant hole drilling rig is positioned on one side of the obstruction and a drill string is used to drill under the obstruction and the drill string is caused to rise to the surface on a selected site on the opposite, or outcropping, side. When the drill string emerges from the earth the loose end with a drill head attached has no further guidance from the bore and drilling action is stopped until a site is prepared for drilling fluid, cuttings, and the like and an arrangement is prepared, at the outcropping location, to change out drill heads and other attachments on the drill string. A larger drill head is usually installed to drill in the opposite direction and the drilling rig proceeds to draw the drill string back toward the drilling rig, enlarging the original bore. If no trouble evolves this process needs little improvement but trouble with horizontal holes is commonplace. Horizontal earth bores are rarely confined to well consolidated formations ideal for well bore wall stability. The bores often cave in on the drill string. Cuttings are hard to manage as the well bore size increases and they frequently cause a string to stick in the bore.
A stuck string often has to be put in compression to loosen the stuck drill head, especially in reverse drilling. Drill strings accept tension quite well but column loads in compression cause buckling, kinking at tool joints, and other problems and various contrivances have been necessary to enable the process to continue. In open country, crawler tractors have been used to pull on the bit end of the drill string either by cable or a surface-to-surface continuous drill string. Either cable or drill string has to be attached at the outcropping end before reverse drilling starts and tool joint connections usually have to be made at both ends as drilling proceeds if continuous drill string is used. Cable damages the bore wall and coordination of a crawler tractor and a drill rig axial control system is difficult at best.
Under ideal circumstances a drill string suspended between separated locations by tension alone will describe an arcuate line and no wall loads would be applied to a well bore having an identical arcuate centerline. Such circumstances rarely occur but illustrate the reduced bore wall loads in most well bores classed as horizontal when tension is applied to both ends of the practical drill string. Full length tension, in nearly all such bores, preserves bore wall conditions and reduces formation break down and string sticking.
Winches have been used to apply tension to the drill head end of the drill string but winches cannot apply compression forces upon the drill string and the destructive cable is still present. Winches are commonly used in built up areas and a disorganized work area is already an environmental burden.
There is a need for apparatus that can receive the outcropping drill string and manipulate the tension, compression and breakout and make-out of connections in a developed, well organized, manner. Additionally, the continuous drill string system invites pumping drilling fluid from both ends of the drill string to clear cuttings and to maintain the wall conditioning of the bore in both directions from a mid string drill head. Further, the time when fluid and cuttings could be randomly disposed of at either end of the drill string has come to an end.
It is therefore an object of this invention to provide manipulation apparatus for the outcrop end of a horizontal surface-to-surface earth bore that can apply either tension or compression to the drill string, provide tool joint breakout and make-up means, and drilling related fluid flow controls in a composite, highway transportable, framework.
It is another object to provide manipulation apparatus for the outcropping end of the drill string and flow controls to direct drilling fluids to the outcropping end of the drill string.
It is yet another object to provide drill string manipulation apparatus for the outcropping end of the drill string that has powered ground anchor screws to support, position, and restraint for the related framework.
It is still a further object to provide a framework for the manipulation apparatus having a powered screw anchoring arrangement on a ground contour frame with a hinge attached pipe handling frame that has power tilting means to align the pipe handling frame with the bore hole direction at the outcropping end.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.